Viral marketing, which is especially effective on the Internet, is a form of marketing in which every new user who interacts with a marketing message plugs her social network into the communication chain.

For example, a social media user who comes across an advertisement that she likes could share this ad with everyone in her social network with the simple click of a button. Each new recipient can also share it with her network. In this way, the advertising message can spread exponentially in a very short period of time.

This is an advertiser’s dream because it costs no extra advertising dollars for the message to reach a huge audience.